1. Field of the Invention
The invention relates to a road milling machine, in particular small milling machine, for working road surfaces, as well as to a method for mounting a cantilevered milling drum.
2. Description of the Prior Art
A quick-change system for milling drums is known from EP 1 194 651 A in which the milling drum is divided and comprises a basic drum body and a milling tube suitable for pushing onto the basic drum body. As only the milling tube needs to be replaced, handling for the replacement of a milling drum is facilitated so that the time and amount of work required for the replacement are minimized. However, said quick-change system essentially relates to large milling machines with a milling drum diameter of approx. 1 m and a milling width ranging between 1.50 m and 4.40 m.
In small milling machines, on the other hand, the milling drum is of an integral design. The length of a milling drum for a small milling machine is typically smaller than its diameter. For example, milling drums for small milling machines have a diameter ranging from 460 mm to 750 mm at a width of between 250 mm and 600 mm.
A further difference between the milling drums of a small milling machine and a large milling machine is that, on the outer circumference of milling drums for small milling machines, toolholders are welded directly onto the drum whereas, with milling drums for large milling machines, quick-change toolholders are used in which a basic part is welded onto the drum which accommodates a toolholder in a replaceable fashion.
Such a small milling machine is known, for example, under the designation Wirtgen W 50 DC. The basic design of a generic road milling machine is known from DE 103 47 873 A1.
The small milling machine comprises a milling drum that is supported at the machine frame in a drum casing and can be driven by a milling drum drive.
The known milling drum drive comprises a drum gearbox which, at its free end, comprises a connecting flange with axially projecting stud bolts for mounting the milling drum. The stud bolts engage with a connecting flange of the milling drum in drill holes arranged accordingly so that the milling drum can be fastened at the drum gearbox by means of nuts. Furthermore, the drum gearbox may comprise a centering spigot which interacts with a corresponding central opening in the connecting flange of the cantilevered milling drum.
The milling drums used for small milling machines usually have a high weight of, for example, up to 300 kg. They are therefore too heavy to allow manual mounting. Handling an integrally designed milling drum for small milling machines is additionally made more difficult due to the fact that the connecting flange is not arranged in the centre of the milling drum axially as approx. two thirds of the interior space of the milling drum is taken up by the milling drum drive. In view of this, the connecting flange of a milling drum for small milling machines is usually located in the vicinity of the front end of the milling drum opposite the drive. Due to the resulting eccentric position of the centre of gravity relative to the connecting flange, the milling drum tilts over the connecting flange during handling. There is also the fact that, when replacing the milling drum under practical conditions, the ground is frequently uneven so that replacing the milling drum is made significantly more difficult. The tools positioned on the milling drum create an irregular three-dimensional surface structure of the milling drum, which results in said milling drum assuming a not clearly definable tilted position on a transport device, such as a forklift truck. Once the milling drum with its heavy weight rests on the lifting device, it can no longer be turned on said lifting device. In view of this, mounting a milling drum at the drum gearbox is extremely difficult even with the aid of a lifting device, in which process the projecting stud bolts of the drum gearbox can easily be damaged and must then be replaced with additional mounting effort.